This invention is generally directed to toner and developer compositions, and more specifically, the present invention is directed to developer and toner compositions containing novel polyimide-imine resins, and process for the preparation thereof. In embodiments, there are provided in accordance with the present invention, toner compositions comprised of polyimide-imine resins, and pigment particles comprised of, for example, carbon black, magnetites, or mixtures thereof, cyan, magenta, yellow, blue, green, red, or brown components, or mixtures thereof, thereby providing for the development and generation of black and/or colored images. In embodiments, there are provided in accordance with the present invention toners with a polyimide-imine resin of the following formula, and which resins are preferably obtained by melt condensation processes ##STR2## X can generally be aryl, diaryl, or cycloaliphatic, and is attached or bonded to the four imide carbonyl moieties; and more specifically X is a tetravalent aromatic or diaromatic radical or group wherein m and n represent the number of random monomer segments, m is preferably from about 100 to about 10,000 and n is preferably from about 10 to about 1,000; R is alkyl, oxyalkylene, or polyoxyalkylene such as as an alkylene oxide like diethylene oxide, triethyleneoxide or polyoxypropylene; and R' is an alkylene with, for example, from about 1 to about 23 carbons, an aryl like phenyl or alkyl. The toner compositions of the present invention in embodiments possess a number of advantages including deinkabilility, that is for example the ease with which toner is removed from paper and subsequently separated from the pulp during the recycling process as practiced by the paper and pulping industries, low melting characteristics, excellent blocking characteristics, possess excellent admix characteristics, and low relative humidity sensitivity such as from about 1.01 to about 2.3. Aryl can include components with from 6 to about 30 carbon atoms such as phenyl, naphthyl, benzyl and the like. Alkylene includes components with from 2 to about 25 carbon atoms such as ethylene, propylene, butylene, pentylene, and the like. Alkyl includes components with 1 to about 25 carbon atoms; and aliphatic includes alkyl.
The toner composition of the present invention can in embodiments be generated by a preparative process involving the melt polycondensation of about 0.85 mole equivalent of dianhydride, such as pyromellitic dianhydride, from about 0.15 mole equivalent of a dialdehyde, such as terephthaldicarboxaldehyde, and of from about 1 mole equivalent of an alkylene diamine, or preferably a diamino terminated alkylene oxide, such as the diamino terminated polyalkylene oxide available from Texaco Chemicals as JEFFAMINE D-230.TM.D-400.TM.D-700.TM.EDR-148.TM., EDR-192.TM. as illustrated by the formula ##STR3## wherein
______________________________________ EDR-148 n = 2; R = H EDR-192 n = 3; R = H D-230 n = 2, 3; R = CH.sub.3 D-400 n = 5, 6; R = CH.sub.3- ______________________________________
The aforementioned resins exhibit a number average molecular weight of from about 1,500 to about 50,000 grams per mole as measured by vapor phase osmometry, and a ! ]lass transition temperature of from about 40.degree. C. to about 80.degree. C., and more preferably of from about 50.degree. C. to about 65.degree. C. as measured by the Differential Scanning Calorimeter. In another embodiment, the polyimide-imine can be generated by a preparative process involving the reaction of about 0.7 mole equivalent to about 1 mole equivalent of a symmetrical mesogenic dianhydride, such as pyromellitic dianhydride, and of from about 0.7 to about 1 mole equivalent of an alkylene diamine, or preferably diamino terminated alkylene oxides such as the diamino terminated polypropylene oxide or diamino terminated polyethylene oxide available from Texaco Chemical as JEFFAMINE.TM., and a dialdehyde, such as terephthaldehyde or 1,4-butyldialdehyde, selected in an amount of from about 0.1 mole equivalent to about 0.3 mole equivalent, and which is believed to impart good deinkability to the resulting toner by formation of the imine moieties in the polyimide-imine resin, and which polyimide-imine resin with a number average molecular weight of from about 1,500 to about 50,000 grams per mole as measured by vapor phase osmometry, and a glass transition temperature of from about 40.degree. C. to about 70.degree. C., and more preferably of from about 50.degree. C. to about 64.degree. C. as measured by the Differential Scanning Calorimeter.
Examples of advantages of the toner composition of the present invention comprised of polyimide-imine include deinkability from paper during recycling. Paper recycling has become an important environmental issue in recent years, and deinking of conventional dry toner images can be a much more difficult problem for the paper recycling industry than that of conventional impact printing inks. The recycling industry utilizes various processes, but the first step is usually to repulp the waste paper in an agitated caustic bath. More specifically, the process involves shredding the paper in an agitated aqueous slurry of about 10 percent consistency by weight of paper at a pH of about 11. The aforementioned pH is attained by the addition of caustic soda or sodium bicarbonate. The aqueous slurry is then heated at 145.degree. C. for a duration of from about 45 minutes to about 60 minutes. During this repulping stage, the paper absorbs large amounts of water, swells considerably, and is reduced to a slurry of individual hydrated pulp fibers. During this process, various inks are detached from the fibers by differential swelling or disintegration. Dry toner images do not usually swell because of their hydrophobic polymeric composition, and they are not usually degraded by chemical hydrolysis. Dry toner images result in flat platelets about 100 to 200 microns in average diameter and about 10 microns in thickness as measured by microscopic image analysis methods. Conventional impact printing inks a re found to disintegrate into much smaller particles, typically 10 microns or less in diameter, primarily because they contain no fused thermoplastic binder resins.
Subsequent steps in the deinking process are designed to remove the liberated ink specks from the hydrated pulp slurry. With small specks liberated from impact-printed papers, these steps are simple and efficient. One or two washing cycles are often sufficient to rinse the small liberated ink specks from the slurry to adequate cleanliness. If this is insufficient, a flotation cell can be added to further clean the pulp. In case the waste paper is imaged with dry toner, the slurry contains the much larger aforementioned toner platelets. To achieve adequate cleaning of such pulps the recycling industry has found it necessary to employ a much more elaborate process. Typically, this comprises six flotation cells in series. Subsequently, the pulp is dewatered in preparation for a high-shear dispersion step to further break up the remaining specks. The dispersion step is energy intensive, and is accompanied by a certain amount of fiber damage. Following this and a redilution step, up to another four flotation steps may be required to remove the broken specks to an adequate cleanliness.
In the present invention, the toner compositions are comprised of a polyimide-imine resin. Under the caustic repulping conditions of a pH of about 11, the imine functionality hydrolyzes and decomposes to oligomeric polyimide residues. This causes the toner particles to break up to less than or equal to about 25 microns, and preferably from about 15 microns to about 25 microns in average volume diameter. This enables the use of the aforementioned simple ink speck removal process typically effective only for impact-printed papers. Therefore, the toner ink specks are much easier to remove, resulting in a more economical process and better quality pulp.
Other advantages associated with toner compositions of this invention in embodiments include low fusing temperatures, such as from about 120.degree. C. to about 140.degree. C., and thus lower fusing energies are required for fixing thereby enabling less power consumption during fusing, and permitting extended lifetimes for the fuser system selected. Furthermore, the toner composition of this invention possesses a broad fusing latitude, such as from about 40.degree. C. to about 100.degree. C., with minimal use of release oil or avoidance of release oil, which inhibits the toner from offsetting onto the fuser rollers usually associated with ghosting or background images on subsequent copies. Furthermore, the fused image obtained from the toner compositions of the present invention in embodiments does not substantially offset to vinyl covers, such as those utilized for notebook binders, and possess low humidity sensitivity ratio of from about 1 to about 2.3 as calculated by the ratio of the triboelectric charge (in microcoulombs per gram) of the developer after placed in a chamber of 20 percent humidity for 48 hours, to the triboelectric charge (in microcoulombs per gram) of the developer after placed in a chamber of 80 percent humidity for 48 hours.
In designing resins for toner composition, it is generally desired that the glass transition temperature of the resin be from about 50.degree. C. to about 65.degree. C., and preferably no less than about 55.degree. C. so that, for example, the toner particles do not aggregate, coalesce or block during manufacturing, transport or storage or until the toner is required for the fixing step. Additionally, low fusing characteristics are required, hence the resin should melt or flow as low in temperature as possible such as from about 120.degree. C. to about 145.degree. C. Moreover, low relative humidity sensitivity of toners are desired such that the triboelectric charge is stable to changes in environmental humidity conditions.
Thermotropic liquid crystalline polyimide resins are illustrated in U.S. Pat. No. 5,348,930, the disclosure of which is totally incorporated herein by reference, which illustrates toner and developer compositions with thermotropic liquid crystalline polyesters, polyamides, and polycarbonates. The toner composition of this invention differs in that, for example, the polyimide structure does not contain the moieties illustrated, which are believed necessary to impart deinkability characteristics. The aforementioned deinkability characteristics of the toners of this invention are attained by the ease in effecting hydrolysis of the imine functionality in caustic conditions, such as from about pH of 10 to about a pH of 14, and resulting in the degradability of resin, hence deinkability of toner from paper fiber and/or pulp.
There is disclosed in copending application U.S. Ser. No. 144,075 toner compositions comprised of a crosslinked polyimide resin and pigment, and process thereof. There is also disclosed in copending application U.S. Ser. No. 144,918 gloss switching toners with certain polyimides. The toner compositions of the copending application U.S. Ser. No. 144,075 are crosslinked to about 30 gel or more and are believed to yield with broad fusing latitude characteristics, and moreover result in low gloss characteristics and not high gloss. The toner composition of this invention are not crosslinked and also contain imine moieties necessary for good deinkability.
Polyimide resins, liquid crystalline polyimide resins and more specifically polyimide resins are also known, such as summarized and illustrated in the Encyclopedia of Polymer Science and Engineering, 2nd Edition, Volume No. 12, published by Wiley (1985). However, these polyimide resins are wholly aromatic and useful as high performance materials, and no mention for use as toners are described in this reference. Specifically that polyimide-imine resins with flexible diamino alkane moieties and, more specifically, polyoxyalkylene moieties are not mentioned, and we believe to be novel class as illustrated herein this invention.
Illustrated in the following copending applications, the disclosures of each being totally incorporated herein by reference, are:
U.S. Ser. No. 144,075 illustrates a toner composition comprised of a pigment and a crosslinked polyimide; and wherein the crosslinked polyimide can be obtained from the reaction of a peroxide with an unsaturated polyimide of the formula ##STR4## R is alkyl, polyoxyalkyl or oxyalkylene; and m represents the number of monomer segments present and is, for example, a number of from about 10 to about about 1,000.
U.S. Pat. No. 5,348,831 illustrates a toner composition comprised of pigment, and a polyester imide resin of the formula ##STR5## wherein n represent the number of segments present and is a number of from about 10 to about 10,000; R' is alkyl or alkylene; and R is independently selected from the group consisting of an oxyalkylene and polyoxyalkylene.
U.S. Ser. No. 144,918 illustrates a toner composition comprised of pigment, and polyimide of the formula ##STR6## wherein m represents the number of monomer segments present; X is ##STR7## thus X can be benzophenone, oxydiphthalic, hexafluoropropane diphenyl, diphenyl sulfone, or biphenyl; and X is attached to four imide carbonyl moieties; and R is independently selected from the group consisting of alkyl, oxyalkylene and polyoxyalkylene.
Specifically, in embodiments, the present invention relates to a toner composition comprised of a pigment, charge control agent and polyimide-imine resins as illustrated herein, and which toners possess deinkability wherein the toner resin decomposes in alkaline or caustic aqueous conditions such as at a pH of from about 10 to a pH of about 14, low fixing of from about 120.degree. C. to about 140.degree. C., high gloss such as from about 50 gloss units to about 80 gloss units as measured by the Garner Gloss metering unit, nonvinyl offset properties and in addition low relative humidity sensitivity such as from about 1.0 to about 2.0 as calculated by Equation 1. These and other advantageous are attained by the toner compositions of this invention comprised of a pigment, optionally a charge control agent and, moreover, a polyimide resin derived from a mesogenic dianhydride and organodiamine, which exhibits low fixing of from about 120.degree. C. to about 140.degree. C., high gloss such as from about 50 gloss units to about 80 gloss units, nonvinyl offset properties and low relative sensitivity such as from about 1.0 to about 2.3.